Refrigeration systems



un 3. 9 J. R. HARNISH 3,

REFRIGERATION SYSTEMS Filed April 19, 1966 24 FIG.|.

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JAMES R. HARNISH,

3,324,671 Patented June 13, 196? 3,324,671 REFRIGERATION SYSTEMS James R. Hamish, Staunton, Va., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., 21 corporation of Pennsylvania Filed Apr. 19, 1966, Ser. No. 549,122 14 Claims. (Cl. 62-174) This invention relates to refrigeration systems in which receivers are used to store refrigerant liquid, and has as an object to control the quantity of refrigerant liquid stored in such a receiver in accordance with superheat in suction gas.

It is well known that in heat pumps more refrigerant is required during cooling operation than during heating operation, and high pressure receivers with heat exchangers have been used to condense and store a portion of the refrigerant charge during heating operation, and to evaporate and return that portion into the systems during cool ing operation. Such heat pumps using such receivers are disclosed in Patent No. 3,006,155 of H. G. Vanderlee et al., and in Patent No. 3,110,164 of G. A. Smith. In the receivers of these patents, refrigerant is condensed by suction gas flowing through their heat exchangers during heating operation, and is stored. During cooling operation, all of the stored refrigerant is evaporated by heat from discharge gas flowing through their heat exchangers, and is forced back into the systems at the inlet sides of their operating expansion means. Thus, these receivers do not store refrigerant during cooling operation.

The heat pump of Patent No. 3,163,016 of E. C. Kennedy uses two storage receivers, one for storing refrigerant during cooling operation, and the other for storing refrigerant during heating operation. As in the previously mentioned patents, refrigerant is condensed for storage by suction gas, and is evaporated for return to the system by discharge gas.

This invention is an improvement on that of the above mentioned Kennedy patent when embodied in a heat pump in that it requires only a single low pressure receiver for storing refrigerant during both cooling and heating operation.

A feature of this invention is that a heat exchanger through which suction gas flows at all times, is arranged to heat or cool refrigerant in a low pressure receiver, with the interior of the receiver connected to the outlet side of the operatin expansion means. \Vhen the suc tion gas has too much superheat, it heats the refrigerant Within the receiver, increasing its vapor pressure, and forcing some of the refrigerant from the receiver into an operating evaporator where it reduces the superheat. When there is insufficient superheat in the suction gas, it cools the refrigerant Within the receiver, reducin its vapor pressure so that refrigerant is sucked from the tubing connected to the evaporator, into the receiver, preventing that refrigerant from entering the evaporator, and thereby increasing the superheat. Thus, refrigerant is added to or drawn from the receiver until thermal equilibrium is reached.

Another feature of another and preferred embodiment of this invention is that a subcooling control valve operating as an expansion valve, maintains a predetermined amount of subcooling of the condensed liquid, and keeps the operating condenser adequately drained while preventing the operating evaporator from becoming starved at low outdoor temperatures to which the operating condenser is exposed. When embodied in a heat pump, the subcooling control valve is the only expansion valve required.

This invention will now be described with reference to the annexed drawings, of which:

FIG. 1 is a diagrammatic view of a preferred heat pump embodying this invention;

FIG. 2 is adiagrammatic sectional view of another form of receiver which may be used instead of the one shown by FIG. 1;

FIG. 3 is a diagrammatic sectional view of still another form of receiver which may be used, and

FIG. 4 is a diagrammatic view of another heat pump embodying this invention.

Description of FIGS. 1, 2 and 3 Referring first to FIG. 1, the discharge side of a refrigerant compressor C is connected by discharge gas tube 10 to a conventional refrigerant reversal valve RV which is connected by tube 11 to an outdoor coil 12. The coil 12 is connected by tube 13, tube 14 containing a checkvalve 15, and tube 16 to the refrigerant inlet side of an expansion valve EV, the refrigerant outlet side of which is connected by tube 18 and tube 19 containing a checkvalve 20 to indoor air coil 22. The coil 22 is connected by tube 23 to the reversal valve RV which is also connected by tube 24 to one end of heat exchanger 25 within low pressure receiver 26. The other end of the heat exchanger 25 is connected by suction gas tube 28 to the suction side of the compressor C. Portions of the tubes 16 and 28 are in heat exchange contact. A tube 30 extends from the bottom of the interior of the receiver 26 to near the top of the latter, and has an open top. The bottom of the tube 30 is connected by tube 31 to the tube 18. The bottom of the tube 30 also has an oil bleed hole 39 therein. The junction of the tubes 14 and 16 is connected by tube 32 containing a check-valve 33 to the tube 19 between the in door coil 22 and the check-valve 20. The tube 13 is also connected by tube 36 containing a check-valve 37 to the junction of the tubes 18 and 19. The heat pump is overcharged with refrigerant so that there is normally a liquid level 40 within the receiver 26.

Preferably, the expansion valve EV is a subcooling control valve such as is disclosed in detail in my Patent No. 3,171,263. The valve EV has a diaphragm chamber 41, the outer portion of which is connected by a capillary tube 42 to thermal bulb 43 in heat exchange contact with the tube 16, and the inner portion of which is connected by capillary equalizer tube 44 to the interior of the tube 16 although the valve EV could be internally equalized. The valve EV responds to the temperature of the refrigerant liquid flowing through the tube 16, and to the pressure of the liquid flowing through the tube 16, or through the valve EV, and maintains a predetermined amount of subcooling, which may be 10 subcooling at a condensing temperature of F., of that liquid. This maintains the coil operating as a condenser adequately drained for good heat transfer. The coil operating as an evaporator is prevented from being overfed by the valve EV through the action of the heat exchanger 25 within the receiver 26 as will be described later.

Referring now to FIG. 2 of the drawings, receiver 26a is similar to the receiver 26 of FIG. 1 except that it does not contain the tube 30, refrigerant flow into and from the interior of the receiver 26a being directly through the tube 31.

Referring now to FIG. 3 of the drawings, receiver 261) is similar to the receiver 26 of FIG. 1 except that the tube 30 is omitted; an oil bleed hole 39 is Within the bottom of the heat eXchanger 25 within the receiver 26b, and the tube 31 instead of being connected to the bottom of the tube 30, is connected to the interior of the receiver 261) above the liquid level 40 therein.

Cooling operation of FIGS. 1, 2 and 3 The solid-line arrows alongside the tubes of FIG. 1 show the direction of refrigerant flow during cooling operation. The compressor C supplies discharge gas through the tube 10, the reversal valve RV which is adjusted for cooling operation, and the tube 11 into the outdoor coil 12 operating as a condenser. Liquid flows from the coil 12 through the tubes 13 and 14, the check-valve 15, the tube 16, the expansion valve EV, the tubes 18 and 19, and the check-valve 20 into the indoor coil 22 operating as an evaporator. Gas flows from the coil 22 through the tube 23, the reversal valve RV, the tube 24, the heat exchanger 25, and the tube 28 to the suction side of the compressor C.

Superheat in the suction gas flowing through the heat exchanger 25 heats or cools the refrigerant within the receiver 26. If there is too much superheat, heat from the gas flowing through the heat exchanger 25 boils liquid within the receiver 26, changing such liquid to gas and increasing its vapor pressure so that gas is forced from the receiver into the open top of the tube 30, and through the tubes 30, 31, 18 and 19, and the check-valve 20 into the indoor coil 22 to reduce the superheat in the suction gas leaving the coil 22. If there is insufficient superheat in the suction gas, the vapor pressure of the refrigerant within the receiver is reduced so that liquid refrigerant is sucked through the tubes 30 and 31 from the tube 18 connected to the outlet side of the expansion valve, preventing that refrigerant from entering the coil 22, thereby increasing the superheat in the suction gas. Thus, refrigerant is withdrawn from or added to the refrigerant within the receiver 26 until there is thermal equilibrium. The coil 22 cannot be overfed by the expansion valve EV because the receiver 26 and its heat exchanger 25 operate to maintain superheat in the suction gas.

Heat from the high pressure liquid flowing through the tube 16 also superheats the suction gas flowing from the heat exchanger 25 through the tube 28 to the suction side of the compressor C, through the heat exchange contact of portions of the tubes 16 and 28, the liquid flowing through the tube 16 being further subcooled by this action.

The expansion valve EV supplies sufllcient refrigerant liquid to the coil 22 to prevent the latter from becoming starved at low outdoor temperatures to which the coil 12 is exposed, and maintains the coil 22 filled with refrigerant liquid at higher outdoor temperatures.

In the receiver 26a of FIG. 2, when there is too much superheat in the suction gas, heat from the heat exchanger 25 boils liquid within the receiver 26a, increasing its vapor pressure, and forcing liquid from the receiver 26a through the tubes 31, 18 and 19, and the check-valve 20 into the indoor coil 22 to reduce the superheat. If there is insufficient superheat, the vapor pressure of the refrigerant within the receiver 26a is reduced so that liquid is sucked through the tube 31 from the tube 18, preventing that liquid from entering the coil 22, thereby increasing the superheat. V

In the receiver 26b of FIG. 3, when there is too much superheat in the suction gas, heat from the heat exchanger 25 boils liquid within the receiver 26b, changing it to gas and increasing its vapor pressure so that gas flows from the interior of the receiver 2611 through the tubes 31, 18 and 19, and the check-valve 20 into the indoor coil 22 to reduce the superheat. If there is insuflicient superheat, the vapor pressure of the refrigerant within the receiver 26b is reduced so that refrigerant liquid is sucked through the tube 31 from the tube 18, into the receiver 261), preventing that liquid from entering the coil 22, and thereby increasing the superheat.

Heating operation of FIGS. 1, 2 and 3 The dashed-line arrows alongside the tubes of FIG. 1 show the direction of refrigerant flow during cooling operation. The compressor C supplies discharge gas through the tube 10, the reversal valve RV which is adjusted for heating operation, and the tube 23 into the indoor coil 22 operating as a condenser; Liquid flows from the coil 22 through the tubes 19 and 32, the check-valve 33, the tube 16, the expansion valve EV, the tubes 18 and 36, and the check-valve 37 into the outdoor coil 12 operating as an evaporator. Gas flows from the coil 12 through the tube 11, thereversal valve RV, the tube 24, the heat exchanger 25, and the tube 28 to the suction side of the compressor C.

The operation of the receiver 26 of FIG. 1, the receiver 26a of FIG. 2, and the receiver 26b of FIG. 3, is the same as that described in the foregoing in connection with cooling operation, except that the suction gas flows from the outdoor coil 12 instead of from the indoor coil 22. Also, the refrigerant not required during heating operation is stored in the operating receiver.

Desoription of FIG. 4

The components of FIG. 4 which are the same as those of FIG. 1 are given the same reference characters. Refrigerant compressor C is connected by discharge gas tube 10 to reversal valve RV which is connected by tube 11 to outdoor coil 12. The coil 12 is connected by tube 13 to one end of capillary tube 50, the other end of which is connected to one end of capillary tube 51. The junction of the tubes 50 and 51 is connected by tube 31 to the bottom of tube 30 within low pressure receiver 26, the tube 30 having an open top near the top of'the interior of the receiver 26. A check-valve 52 is connected across the capillary tube 50, and a check-valve 53 is connected across the capillary tube 51. The other end of the capillary tube 51 is connected by tube 19 to indoor air coil 22 which is connected by tube 23 to the reversal valve RV. The valve RV is connected by tube 24 to one end of heat exchanger 25 within the receiver 26, the other end of which is connected by tube 28 to the suction side of the compressor C.

The capillary tubes 50 and 51 are refrigerant expansion means, the tube 50 serving to expand refrigerant into the indoor coil 22 when the latter is operating as an evaporator, and the tube 51 serving to expand refrigerant into the outdoor coil 12 when the latter is operating as an evaporator.

Cooling operation of FIG. 4

The solid-line arrows alongside the tubes of FIG. 4 show the direction of refrigerant flow during cooling operation. The compressor C supplies discharge gas through the tube 10, the reversal valve RV, and the tube 11 into the outdoor coil 12 operating as a condenser. Liquid flows from the'coil 12 through the tube 13, the capillary tube 50, the check-valve 53, and the tube 19 into the indoor coil 22 operating as an evaporator. Gas flows from the coil 22 through the tube 23, the reversal valve RV, the tube 24, the heat exchanger 25 within the receiver 26, and the tube 28 to the suction side of the compressor C.

When there is too much superheat in the suction gas flowing through the heat exchanger 25, heat from the latter increases the vapor pressure of the refrigerant within the receiver 26, forcing gas into the open top of the tube 30, and through the tubes 30 and 31, the checkvalve 53 and the tube 19 into the indoor coil 22, thereby decreasing the superheat in the suction gas leaving the latter, If there is insufficient superheat in the suction gas flowing through the heat exchanger 25, the latter cools the refrigerant within the receiver 26, reducing its vapor pressure, so that refrigerant is sucked through the tubes 30 and 31 from the outlet of the capillary tube 50, preventing that refrigerant from entering the indoor coil 22, and thereby increasing the superheat in the suction gas leaving the latter.

Heating operation of FIG. 4

The dashed-line arrows alongside the tubes of FIG. 4 show the direction of refrigerant flow during heating operation. The compressor C supplies discharge gas through the tube 10, the reversal valve RV, and the tube 23 into the indoor coil 22 operating as a condenser. Liquid flows from the coil 28 through the tube 19, the capillary tube 51, the check-valve 52, and the tube 13 into the outdoor coil 12 Operating as an evaporator. Gas flows from the coil 12 through the tube 11, the reversal valve RV, and the tube 24 into the heat exchanger 25, and from the latter through the tube 28 to the suction side of the compressor C.

When there is too much superheat in the suction gas flowing through the heat exchanger 25, heat from the latter increases the vapor pressure of the refrigerant within the receiver 26, forcing gas into the open top of the tube 30, and through the tubes 30 and 31, the checkvalve 52, and the tube 13 into the outdoor coil 12, thereby decreasing the superheat in the suction gas leaving the latter. If there is insufiicient superheat in the suction gas flowing through the heat exchanger 25, the latter cools the refrigerant within the receiver 26, reducing its vapor pressure so that refrigerant is sucked through the tubes 30 and 31 from the outlet of the capillary tube 51, preventing that refrigerant from entering the outdoor coil 12, and thereby increasing the superheat in the suction gas leaving the latter. The refrigerant which is not required during heating operation is stored within the receiver 26.

The receivers of FIGS. 2 and 3 could be used in the heat pump of FIG. 4.

Disadvantages of the heat pump of FIG. 4, as compared to that of FIG. 1, are that the coil operating as a condenser is not as well drained; the condensed liquid is not always su bcooled, and the heat pump cannot operate as effectively at low outdoor temperatures as the heat pump of FIG. 1.

The invention is not limited to heat pumps, but can be used in non-reversible cooling systems which would operate as described in the foregoing in connection with cooling operation, with the reversal and check-valves omitted, with the outdoor coil considered as a condenser, and with the indoor coil considered as an evaporator.

What is claimed, is:

1. A refrigeration system comprising a refrigerant compressor, a condenser, means including a discharge gas tube connecting said condenser to said compressor, refrigerant expansion means, means including a liquid tube connecting the inlet of said expansion means to said condenser, an evaporator, a third tube connected to the outlet of said expansion means, means connecting said third tube to said evaporator, a heat exchanger, means including a fourth tu-be connecting said heat exchanger to said evaporator, means including a suction gas tube connecting said heat exchanger to said compressor, a receiver, said heat exchanger being arranged to change the temperature of refrigerant within said receiver, and means connecting the interior of said receiver to said third tube.

2. A refrigeration system as claimed in claim 1 in which said expansion means is a subcooling control valve responsive to the temperature and the pressure of the liquid flowing through said liquid tube.

3. A refrigeration system as claimed in claim 2 in which said means connecting the interior of said receiver to said third tube includes a tube extending from the bottom of the interior of said receiver towards the top of said receiver, said last mentioned tube having an open top.

4. A refrigeration system as claimed in claim 1 in which said means connecting the interior of said receiver to said third tube includes a tube extending from the bottom of the interior of said receiver towards the top of said receiver, said last mentioned tube having an open top.

5. A heat pump comprising a refrigerant compressor, an outdoor heat exchanger, an indoor heat exchanger,

refrigerant expansion means, a receiver heat exchanger, means when cooling is required for routing refrigerant from the discharge side of said compressor through said outdoor heat exchanger operating as a condenser, said expansion means, said indoor heat exchanger operating as an evaporator, and said receiver heat exchanger to the suction side of said compressor, and when heating is required for routing refrigerant from said discharge side of said compressor through said indoor heat exchanger operating as a condenser, said expansion means, said outdoor heat exchanger operating as an evaporator, and said receiver heat exchanger to said suction side of said compressor, a receiver, said receiver heat exchanger being arranged to change the temperature of refrigerant within said receiver, and means connecting the interior of said receiver to the refrigerant inlet of said indoor heat exchanger when the latter is operating as an evaporator, and to the refrigerant inlet of said outdoor heat exchanger when the latter is operating as an evaporator, said receiver heat exchanger being connected to said suction side of said compressor and to the refrigerant outlet of the one of said indoor or outdoor exchangers that is operating as an evaporator.

6. A heat pump as claimed in claim 5 in which said expansion means is a subcooling control valve responsive to the temperature and the pressure of the refrigerant flowing from the one of said outdoor or indoor heat exchangers which is operating as a condenser.

7. A heat pump as claimed in claim 6 in which said connecting means includes a tube within said receiver extending from the bottom of said receiver towards the top of said receiver, said tube having an open top.

8. A heat pump as claimed in claim 5 in which said connecting means includes a tube within said receiver extending from the bottom of said receiver towards the top of said receiver, said tube having an open top.

9. A heat pump comprising a refrigerant compressor, refrigerant reversal means, a discharge gas tu'be connecting said compressor to said reversal means, an outdoor heat exchanger, a second tube connecting one end of said outdoor heat exchanger to said reversal means, an indoor heat exchanger, a third tube connecting one end of said indoor heat exchanger to said reversal means, an expansion valve, a fourth tube connected to the inlet of said expansion valve, a fifth tube connected to the outlet of said expansion valve, a sixth tube connected to the other end of said outdoor heat exchanger, a seventh tube containing a first check-valve connecting said sixth tube to said fourth tube, an eighth tube connected to the other end of said indoor heat exchanger, a ninth tube containing a second check-valve connecting said eighth tube to said fourth tube, a tenth tube containing a third checkvalve connecting said sixth tube to said fifth tube, an eleventh tube containing a fourth check-valve connecting said eighth tube to said fifth tube, a receiver, a heat exchanger arranged to change the temperature of refrigerant within said receiver, a twelfth tube connecting said reversal means to said last mentioned heat exchanger, a suction gas tube connecting said last mentioned heat exchanger to said compressor, and means connecting the interior of said receiver to said fifth tube.

10. A heat pump as claimed in claim 9 in which said expansion valve is a subcooling control valve responsive to the temperature and the pressure of the refrigerant flowing through said fourth tube.

11. A heat pump as claimed in claim 10 in which said connecting means includes a tube within said receiver extending from the bottom of said receiver towards the top of said receiver, and having an open top.

12. A heat pump as claimed in claim 9 in which said connecting means includes a tube within said receiver extending from the bottom of said receiver towards the top of said receiver, and having an open top.

13. A heat pump comprising a refrigerant compressor, refrigerant reversal means, a discharge gas tube connecting the discharge side of said compressor to said reversal means, an outdoor exchanger, a second tube connecting said outdoor heat exchanger to said reversal means, an indoor heat exchanger, a third tube connecting said indoor heat exchanger to said reversal means, a first capillary tube, a first check-valve, means including said capillary tube and said check-valve for flowing refrigerant from said outdoor exchanger when it is operating as a condenser into said indoor heat exchanger operating as an evaporator, a second capillary tube, a second checkvalve, means including said second capillary tube and said second check-valve for flowing refrigerant from said indoor heat exchanger when it is operating as condenser into said outdoor heat exchanger operating as an evaporator, a receiver, a receiver heat exchanger arranged to change the temperature of refrigerant within said receiver, means for flowing refrigerant gas from the one of said indoor or outdoor exchangers that is operating as an evaporator through said receiver heat exchanger to the suction side of said compressor, and means connecting the interior of said receiver to the outlets of said capillary tubes.

14. A heat pump as claimed in claim 13 in which said connecting means includes a tube within said receiver extending from the bottom of said receiver towards the top of said receiver, and having an open top.

References Cited UNITED STATES PATENTS 2,510,881 1/1950 Gerteig 62-509 2,867,094 1/ 1959 Herrick 62174 2,885,868 5/1959 Radclifie 62509 2,901,894 9/ 1959 Zearfoss 62--509 2,977,773 4/ 1961 De Kanter 62-324 3,163,998 1/1965 Wile 62-512 3,232,073 2/ 1966 Jobes 62160 WILLIAM J. WYE, Primary Examiner. 

5. A HEAT PUMP COMPRISING A REFRIGERANT COMPRESSOR, AN OUTDOOR HEAT EXCHANGER, AN INDOOR HEAT EXCHANGER, REFRIGERANT EXPANSION MEANS, A RECEIVER HEAT EXCHANGER, MEANS WHEN COOLING IS REQUIRED FOR ROUTING REFRIGERANT FROM THE DISCHARGE SIDE OF SAID COMPRESSOR THROUGH SAID OUTDOOR HEAT EXCHANGER OPERATING AS A CONDENSOR, SAID EXPANSION MEANS, SAID INDOOR HEAT EXCHANGER OPERATING AS AN EVAPORATOR, AND SAID RECEIVER HEAT EXCHANGER TO THE SUCTION SIDE OF SAID COMPRESSOR, AND WHEN HEATING IS REQUIRED FOR ROUTING REFRIGERANT FROM SAID DISCHARGE SIDE OF SAID COMPRESSOR THROUGH SAID INDOOR HEAT EXCHANGER OPERATING AS A CONDENSER, SAID EXPANSION MEANS, SAID OUTDOOR HEAT EXCHANGER OPERATING AS AN EVAPORATOR, AND SAID RECEIVER HEAT EXCHANGER TO SAID SUCTION SIDE OF SAID COMPRESSOR, A RECEIVER, SAID RECEIVER HEAT EXCHANGER BEING ARRANGED TO CHANGE THE TEMPERATURE OF REFRIGERANT WITHIN SAID RECEIVER, AND MEANS CONNECTING THE INTERIOR OF SAID RECEIVER TO THE REFRIGERANT INELT OF SAID INDOOR HEAT EXCHANGER WHEN THE LATTER IS OPERATING AS AN EVAPORATOR, 